Hegemann began his studies in Berlin, studied art history and economics in Paris and economics at the University of Pennsylvania and in Strasbourg, completing his doctorate in Munich in 1908. Returning to the US, he visited Philadelphia and New York and worked for the "Boston 1915" Exposition, held in Boston in 1909.
Back in Berlin, the following year he was made general secretary of the first international city planning exhibition to be held in Berlin, in 1910. The exhibition aroused great interest and was reprised in refocused form in Düsseldorf; Hegemann wrote an article about it for a general audience and a two-volume official book.
In 1913 he was invited by the People's Institute in New York to give lectures on city planning in several American cities. Again traveling widely, after publishing an extensive report on the Californian cities of Oakland and Berkeley, in 1915 he worked as a city planning consultant. In 1916 he established a firm specializing in suburban planning in the Midwest, with landscape architect Elbert Peets as his partner. In 1922 Hegemann and Peets together published a "thesaurus" of civic art for architects, commenting on about 1200 examples of the discipline, The American Vitruvius.
Returning to Europe in 1921, he became editor of Wasmuths Monatshefte für Baukunst, which became known for its international coverage of architecture and Hegemann's incisive critiques. He wrote debunking biographies of German heroes and, in 1930, the work for which he is best remembered, Das steinerne Berlin: Geschichte der grössten Mietkasernenstadt der Welt (Stony Berlin: History of the Largest Tenement City in the World), which combines historical and architectural criticism. In the introduction he wrote, "It is a German illusion to believe in the possibility of creating an intellectual capital as long as the so-called educated people are almost proud of their inadequate understanding of urban planning." He also wrote political articles and warned against the Nazis, culminating in the book Entlarvte Geschichte (History Unmasked – 1933). He left Germany in May 1933 shortly before his books were burned.
Invited by Alvin Johnson, Hegemann taught urban planning at the New School for Social Research in New York beginning in November 1933. He also taught in the Architecture School at Columbia University. He died suddenly on Easter Sunday, April 12, 1936, after suffering from pneumonia earlier in the year; his last book, the 3-volume City Planning, Housing, intended to supplement and update The American Vitruvius, was completed by 2 co-editors, the last volume appearing in 1938.
Hegemann's travels between Europe and the United States meant that he was an intermediary between architects on both sides of the Atlantic: in particular in The American Vitruvius he refers extensively to European design, taking many examples from his book on the Berlin 1910 exhibition, while in Amerikanische Architektur und Stadtbaukunst he informs German architects of American solutions. However, his emphasis on urban planning rather than purely formal considerations and possibly his having not been present during the development of the Modern Movement in architecture in Europe put him at odds with modernists. For example, in 1929 he was forced to retract an accusation that Martin Wagner's primary activity as chief of city planning for Berlin was funnelling architectural commissions to extremist friends, and he labeled Le Corbusier's Ville Contemporaine project for transforming Paris "only vieux jeu" (old hat) and sarcastically predicted that it was likely to be realized,
[not] because [the skyscrapers] are desirable, healthy, beautiful, and reasonable from the perspective of urban planning but because they are theatrical, romantic, unreasonable, and generally harmful, and because it is part of the money-making activities of a metropolis, in what is literally the world's most international city, Paris, to serve the need for sensation and the vices of native and imported fools.
- Der Städtebau nach den Ergebnissen der Allgemeinen Städtebau-Ausstellung in Berlin, nebst einem anhang: Die Internationale Städtebau-Ausstellung in Düsseldorf; 600 wiedergaben des Bilder- und Planmaterials der beiden Ausstellungen, mit Förderung durch die königlichen preussischen Ministerien des Inneren, des Handels und der öffentlichen Arbeiten, sowie durch die Städte Berlin, Charlottenburg, Rixdorf, Schöneberg, Wilmersdorf, Potsdam, Spandau, Lichtenberg und Düsseldorf. Herausgegeben im Auftrage der Arbeitsausschüsse von Dr. Werner Hegemann, Generalsekretär der Städtebau-Ausstellungen in Berlin und Düsseldorf. 2 vols. Berlin: Wasmuth, 1911, 1913. (German)
- (with Elbert Peets) The American Vitruvius: An Architects' Handbook of Civic Art. New York: Architectural Book Publishing, 1922.
- Amerikanische Architektur und Stadtbaukunst: ein Überblick über den heutigen Stand der amerikanischen Baukunst in ihrer Beziehung zum Städtebau. Berlin: Wasmuth, 1925. (German)
- Das steinerne Berlin: Geschichte der grössten Mietkasernenstadt der Welt. Berlin: Kiepenhauer, 1930. (German)
- Entlarvte Geschichte. Aus Nacht zum Licht. Von Arminius bis Hitler. Leipzig: Hegner, 1933. (German)
- City planning, Housing. 3 vols. Vols. 2 and 3 with William W. Forster and Robert C. Weinberg. New York: Architectural Book Publishing, 1936–38. OCLC 837328
- Werner Oechslin, "Between America and Germany: Werner Hegemann's Approach to Urban Planning," in Berlin/New York: Like and Unlike: Essays on Architecture and Art from 1870 to the Present, ed. Josef Paul Kleihues and Christina Rathgeber, New York: Rizzoli, 1993, ISBN 0-8478-1657-5, pp. 281–95, p. 287.
- Christiane Crasemann Collins, Werner Hegemann and the Search for Universal Urbanism, New York: Norton, 2005, ISBN 0-393-73156-1, p. 35.
- "Die Städtebau-Ausstellung und ihre Lehren," Die Woche; Der Städtebau nach den Ergebnissen der allgemeinen Städtebau-Ausstellung in Berlin, 1911, 1913. Collins, p. 51, p. 373, note 45; p. 375, note 72.
- Edward Marshall, "VASTER SKYSCRAPERS INEVITABLE, SAYS GERMAN EXPERT; Dr. Werner Hegemann, One Of the World's Greatest Authorities on City Planning, Says Our Present High Buildings Mean Intolerable Congestion and Will Be Succeeded by Structures Ten Times as Great but More Widely Separated – Faults of Subways Pointed Out," New York Times magazine, April 6, 1913 (pdf) retrieved December 18, 2010.
- Collins, p. 20.
- "Biographical résumé of Elbert Peets," On the Art of Designing Cities: Selected Essays of Elbert Peets, Ed. Paul David Spreiregen, Cambridge, Massachusetts: MIT, 1966, OCLC 604141820, p. 226.
- Oechslin, p. 292 (translation there).
- Collins, pp. 306, 316.
- Collins, p. 321.
- Collins, p. 335.
- Collins, pp. 362, 363.
- Collins, p. p. 352.
- Oechslin, p. 291, referring to it as City/Planning/Housing.
- Oechsler, p. 290.
- Oechslin, p. 292; p. 295, note 119.
- Oechslin, p. 291, quoting in translation from "Kritik des Grosstadt-Sanierungs-Planes Le Corbusiers," Der Städtebau (1927) p. 70.
- Caroline Flick. Werner Hegemann (1881–1936): Stadtplanung, Architektur, Politik: ein Arbeitsleben in Europa und den USA. Munich: Saur, 2005 (German)